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Versions: 00 rfc2825                                       Informational
Internet-Draft                                    Leslie L. Daigle
Expires October 12, 2000.                         Editor


       A Tangled Web:  issues of I18N, domain names, and the
                  other Internet protocols

                 draft-iab-i18n-dns-00.txt


Status of this Memo

     This document is an Internet-Draft and is in full conformance
     with all provisions of Section 10 of RFC2026.

     Internet-Drafts are working documents of the Internet Engineering
     Task Force (IETF), its areas, and its working groups.  Note that
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0.0 Abstract

The goals of the work to "internationalize" Internet protocols
include providing all users of the Internet with the capability of
using their own language and its standard character set to express
themselves, write names, and to navigate the network. This impacts
the domain names visible in e-mail addresses and so many of today's
URLs used to locate information on the World Wide Web, etc.  However,
domain names are used by Internet protocols that are used across
national boundaries. These services must interoperate worldwide, or
we risk isolating components of the network from each other along
locale boundaries.  This type of isolation could impede not only
communications among people, but opportunities of the areas involved
to participate effectively in e-commerce, distance learning, and
other activities at an international scale, thereby retarding
economic development.

There are several proposals for internationalizing domain names,
however it it is still to be determined whether any of them
will ensure this interoperability and global reach while addressing
visible-name representation.  Some of them obviously do not. This
document does not attempt to review any specific proposals, as that
is the work of the Internationalized Domain Name (IDN) Working Group
of the IETF,  which is tasked with evaluating them in consideration
of the continued global network interoperation that is the deserved
expectation of all Internet users.

This document elaborates the scope of the problem outside of
the domain name system (DNS).


1.0 A Definition of Success

The Internationalized Domain Names (IDN) Working Group
is one component of the IETF's continuing comprehensive effort to
internationalize language representation facilities in the protocols
that support the global functioning of the Internet.

In keeping with the principles of rough consensus, running code,
architectural integrity, and in the interest of ensuring the global
stability of the Internet, the IAB emphasizes that all solutions
proposed to the (IDN) Working Group will have to be evaluated not
only on their individual technical features, but also in terms of
impact on existing standards and operations of the Internet and the
total effect for end-users:  solutions must not cause users to
become more isolated from their global neighbors even if they appear
to solve a local problem.  In some cases, existing protocols have
limitations on allowable characters, and in other cases
implementations of protocols used in the core of the Internet
(beyond individual organizations) have in practice not implemented
all the requisite options of the standards.


2.0 Technical Challenges within DNS

In many technical respects, the IDN work is not different from any
other effort to enable multiple character set representations in
textual elements that were traditionally restricted to English
language characters.

One aspect of the challenge is to decide how to represent the names
users want in the DNS in a way that is clear, technically feasible,
and ensures that a name always means the same thing.  Several
proposals have been suggested to address these issues.

These issues are being outlined in more detail in the IDN WG's
evolving draft requirements document; further discussion is deferred
to the WG and its documents.


2.0 Integrating with Current Realities

Nevertheless, issues faced by the IDN working group are complex and
intricately intertwined with other operational components of the
Internet.  A key challenge in evaluating any proposed solution is the
analysis of the impact on existing critical operational standards
which use DNS names.  Standards-changes can be effected, but the
best path forward is one that takes into account current realities
and (re)deployment latencies. In the Internet's global context, it is
not enough to update a few isolated systems, or even most of the
systems in a country or region.  Deployment must be nearly universal
in order to avoid the creation of "islands" of interoperation that
provide users with less access to and connection from the rest
of the world.

These are not esoteric or ephemeral concerns.  Some specific issues
have already been identified as part of the IDN WG's efforts.


2.1 Domain Names and E-mail

As indicated in the IDN WG's draft requirements document, the
issue goes beyond standardization of DNS usage.  Electronic mail has
long been one of the most-used and most important applications of
the Internet.  Internet e-mail is also used as the bridge that
permits the users of a variety of local and proprietary mail systems
to communicate. The standard protocols that define its use (e.g.,
SMTP (STD10), RFC822, and MIME (RFC2045)) do not permit the full
range of characters allowed in the DNS specification. Certain
characters are not allowed in e-mail address domain portions of
these specifications.  Some mailers, built to adhere to these
specifications, are known to fail when on mail having non-ASCII
domain names in its address -- by discarding, misrouting or damaging
the mail.  Thus, it's not possible to simply switch to
internationalized domain names and expect global e-mail to continue
to work until most of the servers in the world are upgraded.


2.2 Domain Names and Routing

At a lower level, the Routing Policy Specification Language (RPLS)
(RFC2622) makes use of "named objects" -- and inherits object
naming restrictions from older standards (RFC822 for the same e-mail
address restrictions, RFC1034 for hostnames).  This means that until
routing registries and their protocols are updated, it is not
possible to enter or retrieve network descriptions utilizing
internationalized domain names.


2.3 Domain Names and Network Management

Also, the Simple Network Management Protocol (SNMP) uses the textual
representation defined in RFC2579.  While that specification does
allow for UTF-8-based domain names, an informal survey of deployed
implementations of software libraries being used to build
SNMP-compliant software uncovered the fact that few (if any)
implement it.  This may cause inability to enter or display correct
data in network management tools, if such names are internationalized
domain names.


2.4 Domain names and security

In the Transport Layer Security protocol (TLS), it is common usage
that a server displays a certificate containing a domain name
purporting to be the domain name of the server, which the client can
then match with the server name he thought he used to reach the
service.

Unless comparision of domain names is properly defined, the
client may either fail to match the domain name of a legitimate
server, or match incorrectly the domain name of a server
performing a man-in-the-middle attack.  Either failure could enable
attacks on systems that are now impossible or at least far more
difficult.




3.0 Conclusion

It is therefore clear that, although there are many possible ways to
assign internationalized names that are compatible with today's DNS
(or a version that is easily-deployable in the near future), not all
of them are compatible with the full range of necessary networking
tools.  When designing a solution for internationalization of domain
names, the effects on the current Internet must be carefully
evaluated. Some types of solutions proposed would, if put into
effect immediately, cause Internet communications to fail in ways
that would be hard to detect by and pose problems for those who
deploy the new services, but also for those who do not; this would
have the effect of cutting those who deploy them off from effective
use of the Internet.

The IDN WG has been identified as the appropriate forum for
identifying and discussing solutions for such potential
interoperability issues.

Experience with deployment of other protocols has indicated that it
will take years before a new protocol or enhancement is used all over
the Internet.  So far, the IDN WG has benefitted from proposed
solutions from all quarters, including organizations hoping to
provide services that address visible-name representation and
registration -- continuing this process with the aim of getting a
single, scalable and deployable solution to this problem is the only
way to ensure the continued global interoperation that is the
deserved expectation of all Internet users.


4.0 References

STD10           Postel, J.B.  "Simple Mail Transfer  Protocol," STD10,
                1982.

RFC 822 Crocker, D., "Standard for the Format of ARPA
                Internet Text Messages", RFC822, 1982.

RFC1034 Mockapetris, P., "Domain Names - Concepts and Facilities",
                RFC1034, 1987.

RFC2045 Freed, N., and N. Borenstein, "Multipurpose Internet Mail
                Extensions (MIME) Part One:  Format of Internet Message
                Bodies", RFC2045, 1996.

RFC2579 McCloghrie, K., D. Perkins, J. Schoenwaelder, J. Case, and
                M. Rose, "Textual Conventions for SMIv2", RF2579, 1999.

RFC2622 Alaettinoglu, C., C. Villamizar, E. Gerich, D. Kessens,
                D. Meyer, T. Bates, D. Karrenberg, and M. Terpstra,
                "Routing Policy Specification Language (RPSL)", RFC2622,
                1999.


5.0 Editor Contact Information

Leslie L. Daigle
leslie@rattlenote.com